Superamphiphobic plastrons on wood and their effects on liquid repellence

Abstract

The increasing utilization of wood-based products raises new demands for improved durability, for example an enhanced liquid repellence. Superhydrophobic or superamphiphobic surfaces have been widely fabricated. Less attention has been paid to such modifications on wood and the changes of its hygroscopic or solvoscopic properties. In this work, wood veneers were surface modified by hydrophobized silicone nanofilaments. Results revealed that the surface-modified wood showed a superamphiphobic behavior, i.e. it repelled water, ethylene glycol and hexadecane with contact angles greater than 150° and roll-off angles of less than 10°. Most importantly, a plastron effect was observed when the surface-modified wood was submerged in water, ethylene glycol or hexadecane, which reduced the liquid sorption rate and extent to various degrees. By comparing the measured permeabilities and the estimated diffusive mass flux and supported by Hansen solubility parameters and the degrees of swelling, it is concluded that diffusion is the major cause for the liquid uptake in the surface-modified wood. Moreover, the interaction between the liquid and the modified layer (the solubility of the liquid in the modified layer) also needs to be considered, especially in hexadecane.